Length reduction kinetics of multiwalled carbon nanotubes correlated to planetary ball mill impact energy

Abstract

Four commercial multiwalled carbon nanotubes with distinct lengths and diameters were subject to planetary ball milling to induce length reduction. The Burgio-Rojac energy model was employed to calculate the single impact energy and cumulative energy dissipated to the carbon nanotubes during milling. The ratio of sample mass to bead mass and the nanotube bulk density did not affect length reduction during grinding. The minimum impact energy barrier for carbon nanotube length reduction appeared directly proportional to nanotube diameter for parallel wall morphologies, although a nanotube sample with a cup-stacked wall morphology showed a much lower energy barrier. A normalized exponential equation relating carbon nanotube length and cumulative impact energy collapsed all data to a single exponential master curve described by the same scaling parameters, namely a pre-exponential term that includes the initial nanotube length and a scaling energy in the exponent.